TOYOTA OTHER RPM PROBLEM

1987 Toyota Other • 340,000 miles

I have a 1987 2.4 diesel 4wd dualcab hilux with about 340,000kms on it and about two weeks ago it randomly started losing power around 2000Rpms it just drops all acceleration power, but the rpms stays up with the engine and too get it going again I have to press in the clutch and accelerate afterswards and sometimes that dosnt work, I took off the fuel tank and flushed it out and vaccumed it, there was quite abit of rust flakes but I made sure it was spotless before putting it back in, I also blew back the fuel lines from the fuel filter and back, but its still doing the same thing, could it be injecter pump? Faulty autoelectrics?